Aided by the pending arrival of the new Second Avenue subway and some old connections, the Rudin family leases 70,000 square feet at its office property at 845 Third Ave.

One of the city's top real estate families, the Rudins, has been busy at 845 Third Ave., the 21-story office tower it has long owned between East 51st and East 52nd streets. It recently leased nearly 70,000 square feet to a handful of firms.

The largest of those deals came from K2 Intelligence, an international consulting firm. It signed up for a total of 55,440 square feet spread across several floors for nine years, according to Studley's David Carlos, who represented the firm. Included in the transaction were a lease for the entire 15,440-square-foot 15th floor and a sublease of 15,000 square feet on the 13th floor. The firm was already subleasing the fourth floor.

"The strength of midtown east is its transportation access, and proximity to all the residential areas like the Upper East Side," said Bill Rudin, chief executive of Rudin Management Company, who noted that the scale of those transportation benefits will only increase with completion of the East Side Access project. Robert Steinman of Rudin Management Company represented the building's ownership in the deal.

K2 decided to stick with Third Avenue because it also presents a bargain compared to other markets nearby, like the Plaza District, which consistently ranks as one of the priciest areas in the city.

"Midtown east is where you can still get great value in class A assets," said Mr. Carlos, who noted asking rents in the area typically top out at $60 per square foot.

Both landlord and tenant are run by families that have a long history together.

"My father and his business partner's first landlord was Mr. Rudin Sr., at 641 Lexington Ave.," said Jeremy Kroll, chief executive at K2, which is an offshoot of his father's company, which leased with the Rudin family in the 1970s. "We go way back with the family."

The other three firms that recently took space were Cohere Communications, a technology service provider that signed on for 5,649 square feet on the 16th floor; SeniorBridge Family Companies, an eldercare organization that renewed and expanded for a total of 25,295 square feet on the seventh and part of the 11th floors; and the building's retail anchor, The Sports Authority, which renewed its lease for 22,940 square feet on the second, ground and basement floors of the building.